Cooling device for turbine rotors



Dec. 5, 1944. A. BUCHI 2,364,189

COOLING DEVICE FOR TURBINE ROTORS Filed Oct. 15, 1941 2 she ets-sheet lT M J J 5 a 7 4 3+ a lnvenfw? Dec. 5, 1944. A. BUCHI 2,364,189

COOLING DEVICE FOR TURBINE ROTORS Filed Oct. 15, 1941 2 Sheets-Sheet 2Patented Dec. 5, 1944 UNITED STATES PATENT OFFICE 7 2,364,189 COOLINGDEVICE FOR TURBINE ROTORS Alfred Biichl, Winterthm', SwitzerlandApplication October 15, 1941, Serial No. 415,136

In Switzerland September 21, 1940 3 Claims.

parts inherent energy to the turbine buckets and is passed from theinlet to the exit side of the turbine bucket arrangement at the regionof the I base portions of the buckets. However, part of the delivery ofthe cooling fan means may be blown through passages disposed adjacent tothe point of connection of the turbine buckets with the turbine rotor,by which provision the bucket connecting means are additionally cooledand heat conduction towards the body of the turbine rotor is prevented.

The turbine rotor may-be provided with fan blading only on that of itsend faces adjacent the inlet side of the turbine for the power fluid,

or on both end faces. Exteriorly beyond the cooling fan blading diffuseror guide vanes may be arranged in the stationary part of the turbinecasing surrounding the turbine rotor, for conveying the cooling meanstowards the bucket arrangement of the turbine. For the purpose ofobtaining effective transmission of heat from the turbine rotor to thecooling means the fan blades are made integral with the turbine rotor.The fan blading employed may be of any suitable type and the dispositionof the blading may be chosen to suit requirements.

The bearing arrangement of the turbine rotor may be such that the rotorprojects freely therefrom with one rotor end face unobstructed so thatcooling air can be directly guided towards the cooling fan blading fromwithout unimpeded.

In the accompanying drawings embodiments of the invention areillustrated by way of example only, in which Fig. 1 is a sectional viewof a single-stage turbine driven'blower, cooling fan bladings being Ill)arranged on both end faces of the turbine rotor;

Figs. 2, 3 and 4 show details of means for the guidance of the coolingmedium delivery of the cooling fan, and

Fig. 5 shows a section of a single-stage gas turbine driven blowerprovided with cooling fan blading only on the end face of the turbinerotor situated at the inlet side of the turbine for the power fluid.

In Fig. 1, the turbine rotor is designated by I, whereas the numeral 2denotes the blower rotor driven by the turbine rotor. A two-part cooledturbine casing 3 surrounds the blower rotor. The numerals 4 and 5 referto the gas supply conduits leading into the turbine and the nozzleringrespectively, the gases being projected onto the bucket arrangement 6 ofthe turbine rotor I through said ring. The intake of the blower isdesignated by I, and 8 refers to the diffuser casing of the blower. Theturbine rotor I has its bearings 8, I0 in a bearing sleeve I2 inside ofa stationary bearing support I within the blower casing, and the blowerrotor 2 is connected to the turbine rotor I by a sleeve-like extensionI3.

The invention is concerned with the cooling fan bladings I4 and I4arranged on either end face of the turbine rotor I, as shown in. Fig. 1.By the action of the bladings I4, I4 the cooling medium, which may beair or the like, is sucked in in the region of the hub portion of theblower rotor, and is conveyed towards the outer end face of the turbinerotor. During the passage of the air through the bladings I4 and/or I4this air first cools the bucket wheel disc I and keeps on cooling inthis way until it leaves the blading I4 or I4 respectively. Thereuponthe cooling air, when leaving the blading II, is deflected by thestationary diffuser blading I5 into the rotating bucket arrangement 6 ofthe turbine rotor I, so that a film of cold air is blown through thebucket arrangement in between the hot power gases, which pass throughthe turbine bucket arrangement 6 at a point disposed radially furtheroutward, and the base extensions I9 of the buckets. By this means notonly the end walls of the turbine rotor, the base extensions I9 and theinner portions I8 of the buckets are cooled, but the heat flux passingfrom the hot gases conveyed through the outermost portions of thebuckets 6 towards the body of the rotor I is considerably reduced at thesame time and theradially outer bucket portions are also cooled. Coolingair is suplied from without at the inlet side of the turbine through thesupply funnel I6, if, as shown in Fig. 1, a freely projecting turbinewheel with an unobstructed outer end faceis used.

The air drawn in and delivered by the cooling fan blading I4 is suppliedto the latter from without through bores 25. The numeral l5 refers ,tocooling air difluser blades being, for example,

arranged exteriorly of the fan rotor in the stationary part of'theturbine, and, if desired, sunk in the material of said part. Thediffuser blades l deflect the air delivered by the blading It to theright in Fig. 1 into the inner portion of the turbine buckets 6,advantageously, at such an angle that in addition to producing a coolingeffect this air imparts inherent energy thereof to the turbine rotor I.In order to provide for deflecting the cooling air with as little lossof energy as possible on the turbine rotor l at a point radially beyondthe cooling fan blading II a .thickened portion l'l aerodynamicallyimproving f iethe deflecting of the cooling medium into the 'difluserblades l5 may be arranged on one or both end faces of said rotor.

Fig. 2 is a view of a segment of the turbine bucket arrangement on alarger scale showing the path along which the cooling air flows throughthe turbine bucket arrangement 6. The radially inner portions 18 of theturbine bucket arrangement 6 are cooled by the air passing out of thediffuser blading l5 for the cooling air. The base extensions IQ of theturbine buckets 6 are so shaped that adjacent to the joints 2| betweenthe individual buckets and, upon choice,

also in the adjoining portions of the turbinerotor I, passages 20 areformed throughwhich at least part of the air output of the cooling fanis conveyed towards the exit side of the turbine buckets 6. By thismeans the base extensions l9 and the radially outer portions of theturbine rotor I are cooled. In order that the turbine bucket arrangement6 is, nevertheless, firmly secured to the turbine rotor l thearrangement is so chosen that adjacent turbine buckets touch each otheron the outside of the surfaces 2|.

In an arrangement of the base portions 19 as shown in Fig. 2, forexample, also the cylindrical base extensions 22 of the buckets areprovided with passages 23. Through the passages 23 a further portion ofthe air delivered by the cooling fan will pass and thus additionallycool the base extensions 19 directly, whereby the turbine rotor l iscooled indirectly, in addition. By virtue of the cooling thus providednot only the temperature of the turbine rotor and that of the baseextensions is brought down and, consequently. greater strength ofmaterial is obtained for these parts even at high temperatures of thepower gas,

but also reduced straining due to expansion by heat of the parts fittedtogether results, and improved resistivity of the assembly at the sametime.

Alternatively, part of the cooling air at least may, as also shown inFig. 2, be passed through bores 26 provided in the turbine buckets 6which bores receive, for example, the cooling air leaving the passages20, or other cooling air. By this means the buckets 6 are directlyadditionally cooled over all the length thereof and, advantageously,near their entrance portions for the hot gases.

In Fig. 3 the cooling fan blades, which are designated by l4, arepreferably in the form of radial blades for reasons of strength. Thisblade arrangement ensures minimum straining of the turbine rotor and, ifmade integrally with the turbine rotor I, maximum heat transmission fromthe rotor to the cooling medium is ensured at the same time. By the flowof air passing through between the blades l4 and It the turbine rotor issatisfactorily cooled.

In Fig. 4 the stationary difl'user blade arrangement ii for deflectingthe cooling air into the blower having a cooling fan blading ll only onthe end face of the rotor l adjacent the gas inlet side of the turbine.

I The invention can be applied also to turbines into which the powerfluid is introduced in various other directions of flow, and may furtherbe applied to individual rotors or all the rotors of multi-stageturbines. The invention has the great advantage that a considerableproportion of the energy consumed for the conveyance of the coolingmedium is recovered and any substantial losses. due to change ofdirection of flow are avoided.

Owing to the temperature of the cooling medium rising already while thelatter cools the turbine rotor disc, the gathering up of heat by saidmedium is more effective than if the cooling medium would be conductedinto the turbine bucket arrangement directly from outside without beingpreheated.

I claim:

1. In a cooling device for turbine rotors for hot power fluids, aturbine rotor having a disc-shaped wheel body. a bucket arrangementdisposed on said wheel body, cooling fan blading means provided on saidwheel body in driving association with said rotorfor delivering acooling medium, a casing forsaid rotor including ide walls, the wall onthe inlet side of the turbine providing conduction means for saidcooling medium, delivered by said fan blading means for directing thecooling medium outwardly, sweeping and thus cooling said wheel body andthen changing the direction of flow of the cooling medium at theperiphery of the wheel body so as to pass axially across the rotorperiphery to form a cooling and insulating layer to 'cool and protectthe roots of the buckets and the rotor body from hot gases,

2. In a cooling device for turbine rotors for hot power fluids, aturbine rotor having a disc-shaped wheel body, a bucket arrangementdisposed on said wheel body, cooling fan blading means provided on saidwheel body in driving association with said rotor for delivering acooling medium, a casing for said rotor including side walls, the wallon the inlet side of the turbine providing conduction means for saidcooling medium, delivered by said fan blading means for directing thecooling medium outwardly, sweeping and thus cooling said wheel body andthen changing the direction of flow of the cooling medium at theperiphery of the wheel body so as to pass axially across the rotorperiphery to form a cooling and insulating layer to cool and protect theroots of the buckets and the rotor body from hot gases, forwardlyinclined vanes arranged in the conduction means of the casing exteriorlybeyond said cooling fan blading means immediately adjacent the rotorbody for guiding said cooling medium towards said bucket arrangement andin the direction of movement thereof, and thickenings disposed on anunobstructed end face of said rotor, in advance of sold inclined vanesasregards the flow or said cooling medium, for aerodynamically improvingthe passage of said flow into said inclined vanes.

3. In a cooling device for turbine rotors for hot power fluids, aturbine rotor having a disc-shaped wheel body, a bucket arrangementdisposed on said wheel body, cooling fan blading means provided on saidwheel body in driving association with said rotor for delivering 'acooling medium, a casing for said rotor including side walls, the wallon the inlet side of the turbine providing conduction means for saidcooling medium, delivered by said fan blading means for directing thecooling medium outwardly, sweeping and thus cooling said wheel body andthen changing the direction of flow of the cooling medium at theperiphery oi the wheel body so as to pass axially across the rotorperiphery to form a cooling and insulating layer to cool and protect theroots of the buckets and the rotor body from hot gases, forwardlyinclined flow-directing vanes arranged in the conduction means 01' thecasing exteriorly beyond said cooling fan blading means immediatelyadjacent the rotor body for guiding said cooling medium in the directionof movement of said bucket arrangement, and thickenings disposed on bothend faces of said rotor radially outwardly of said fan blading means inop;- position to the cooling medium inlet end of said vanes, foraerodynamically improving the flow of cooling medium toward the turbineexit. V

ALFRED BUCHI.

